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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : /* Character/text operations. */
       8             : 
       9             : #ifndef mozilla_TextUtils_h
      10             : #define mozilla_TextUtils_h
      11             : 
      12             : #include "mozilla/Assertions.h"
      13             : #include "mozilla/TypeTraits.h"
      14             : 
      15             : namespace mozilla {
      16             : 
      17             : namespace detail {
      18             : 
      19             : template<typename Char>
      20             : class MakeUnsignedChar
      21             :   : public MakeUnsigned<Char>
      22             : {};
      23             : 
      24             : template<>
      25             : class MakeUnsignedChar<char16_t>
      26             : {
      27             : public:
      28             :   using Type = char16_t;
      29             : };
      30             : 
      31             : template<>
      32             : class MakeUnsignedChar<char32_t>
      33             : {
      34             : public:
      35             :   using Type = char32_t;
      36             : };
      37             : 
      38             : } // namespace detail
      39             : 
      40             : /** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
      41             : template<typename Char>
      42             : constexpr bool
      43             : IsAscii(Char aChar)
      44             : {
      45             :   using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
      46     2454190 :   auto uc = static_cast<UnsignedChar>(aChar);
      47     1229247 :   return uc < 0x80;
      48             : }
      49             : 
      50             : /**
      51             :  * Returns true iff |aChar| matches [a-z].
      52             :  *
      53             :  * This function is basically what you thought islower was, except its behavior
      54             :  * doesn't depend on the user's current locale.
      55             :  */
      56             : template<typename Char>
      57             : constexpr bool
      58             : IsAsciiLowercaseAlpha(Char aChar)
      59             : {
      60             :   using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
      61       53133 :   auto uc = static_cast<UnsignedChar>(aChar);
      62       53133 :   return 'a' <= uc && uc <= 'z';
      63             : }
      64             : 
      65             : /**
      66             :  * Returns true iff |aChar| matches [A-Z].
      67             :  *
      68             :  * This function is basically what you thought isupper was, except its behavior
      69             :  * doesn't depend on the user's current locale.
      70             :  */
      71             : template<typename Char>
      72             : constexpr bool
      73             : IsAsciiUppercaseAlpha(Char aChar)
      74             : {
      75             :   using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
      76        6706 :   auto uc = static_cast<UnsignedChar>(aChar);
      77        6706 :   return 'A' <= uc && uc <= 'Z';
      78             : }
      79             : 
      80             : /**
      81             :  * Returns true iff |aChar| matches [a-zA-Z].
      82             :  *
      83             :  * This function is basically what you thought isalpha was, except its behavior
      84             :  * doesn't depend on the user's current locale.
      85             :  */
      86             : template<typename Char>
      87             : constexpr bool
      88       52535 : IsAsciiAlpha(Char aChar)
      89             : {
      90       59839 :   return IsAsciiLowercaseAlpha(aChar) || IsAsciiUppercaseAlpha(aChar);
      91             : }
      92             : 
      93             : /**
      94             :  * Returns true iff |aChar| matches [0-9].
      95             :  *
      96             :  * This function is basically what you thought isdigit was, except its behavior
      97             :  * doesn't depend on the user's current locale.
      98             :  */
      99             : template<typename Char>
     100             : constexpr bool
     101             : IsAsciiDigit(Char aChar)
     102             : {
     103             :   using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
     104     2060082 :   auto uc = static_cast<UnsignedChar>(aChar);
     105     2060082 :   return '0' <= uc && uc <= '9';
     106             : }
     107             : 
     108             : /**
     109             :  * Returns true iff |aChar| matches [a-zA-Z0-9].
     110             :  *
     111             :  * This function is basically what you thought isalnum was, except its behavior
     112             :  * doesn't depend on the user's current locale.
     113             :  */
     114             : template<typename Char>
     115             : constexpr bool
     116             : IsAsciiAlphanumeric(Char aChar)
     117             : {
     118        1153 :   return IsAsciiDigit(aChar) || IsAsciiAlpha(aChar);
     119             : }
     120             : 
     121             : /**
     122             :  * Converts an ASCII alphanumeric digit [0-9a-zA-Z] to number as if in base-36.
     123             :  * (This function therefore works for decimal, hexadecimal, etc.).
     124             :  */
     125             : template<typename Char>
     126             : uint8_t
     127           0 : AsciiAlphanumericToNumber(Char aChar)
     128             : {
     129             :   using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
     130         851 :   auto uc = static_cast<UnsignedChar>(aChar);
     131             : 
     132         851 :   if ('0' <= uc && uc <= '9') {
     133         470 :     return uc - '0';
     134             :   }
     135             : 
     136           0 :   if ('A' <= uc && uc <= 'Z') {
     137             :     return uc - 'A' + 10;
     138             :   }
     139             : 
     140             :   // Ideally this function would be constexpr, but unfortunately gcc at least as
     141             :   // of 6.4 forbids non-constexpr function calls in unevaluated constexpr
     142             :   // function calls.  See bug 1453456.  So for now, just assert and leave the
     143             :   // entire function non-constexpr.
     144             :   MOZ_ASSERT('a' <= uc && uc <= 'z',
     145             :              "non-ASCII alphanumeric character can't be converted to number");
     146             :   return uc - 'a' + 10;
     147             : }
     148             : 
     149             : } // namespace mozilla
     150             : 
     151             : #endif /* mozilla_TextUtils_h */